This invention relates to a vertically integratable circuit and a method for producing same.
Vertically integratable circuits refer to semiconductor circuits produced by planar technology which are disposed vertically one above the other in several levels, resulting in three-dimensional circuits. The single components and circuit elements of the different levels are electrically interconnected by vertical contacts. This permits higher packing density to be attained compared to two-dimensional circuits, i.e. circuits in only one level. Vertical integration also offers advantages in terms of security since especially sensitive circuit elements can be disposed in levels or layers surrounded on both sides by at least one further level or layer with active components.
In the production of the three-dimensional circuits, in particular the vertical contacts deviate from known technologies since the single vertically integratable circuits are produced by known and readily controllable planar technology. Several methods have become known for producing the vertical contacts.
One known method is based on depositing polycrystalline silicon on a finished component layer and recrystallizing it. Further components can be fabricated in the recrystallized layer. The disadvantage of this method is that the high temperatures during recrystallization can change the properties of the finished active components of the lower level. Furthermore, the serial processing of the vertically integrated overall circuit results in an accordingly longer turnaround time for production.
In another known method it is provided that the single vertically integratable circuits or levels of circuits are produced separately on different substrates. Substrates with single circuit levels are then thinned, provided with front side and backside contacts and connected vertically by a bonding method. The disadvantage of this method is that the front side and backside contacts are produced partly using materials not readily usable in known semiconductor manufacturing processes.
DE 44 33 845 A1 discloses a method for producing a three-dimensional integrated circuit wherein two finished substrates or single circuits are interconnected. For vertical electric connection of the circuits contained on both substrates, further process steps are performed to produce a metalization after connecting the two substrates one of which was thinned. The disadvantage of the known method is that completely processed substrates must be made available and additional process steps are required for producing the vertical electric connection.
The problem of the present invention is thus to state a vertically integratable circuit and a method for producing same that manages with fewer process steps.